Gamma knife radiosurgery in the management of endolymphatic sac tumors.

Background: Although widely regarded as rare epithelial tumors with a low grade of malignancy, endolymphatic sac tumors (ELST) often lead to disabling petrous bone destruction and significantly impairing symptoms at the time of primary diagnosis and/or recurrence. ELST is not uncommon in von Hippel Lindau (VHL) patients. Although open surgery is regarded as the best treatment option, recurrence remains a challenge, particularly when gross tumor resection (GTR) is deemed unachievable due to topographic conditions. Tumor recurrence successfully treated with fractionated radiotherapy and radiosurgery have been reported in selected cases. We present the case of a patient with recurrent ELST treated with salvage gamma knife radiosurgery (GKRS) adding a review of current literature.

Case Description: A 65-year-old patient underwent GKRS of an unresectable, recurrent ELST. Tumor volumetric analysis showed almost 15% increase in tumor volume in the 4 months between the pre-GKRS magnetic resonance imaging (MRI) and the stereotactic MRI (s-MRI) at treatment. Follow-up MRI at 12 and 20 months showed significant decrease in local tumor volume, decreased contrast enhancement and no perifocal edema. The patient's general and neurological status remains stable to the present day.

Conclusion: In the present case, GKRS was effective in the management of a recurrent ELST over the course of 20 months. Because of ELSTs recurrence potential, long-term follow up is required. The present case as well as previous reports might suggest a possible salvage/adjunctive role of radiosurgery in the management of ELST. Further studies are deemed necessary.